Alphabet of Lines Chapter 3 Sacramento City College EDT 300/ ENGR 306 EDT 300/306 - Basic Technical Drafting 1 Alphabet of Lines The design industry has agreed on a set of standard lines that are used to represent various objects. The American Society of Mechanical Engineers (ASME) has developed this standard which is accepted throughout the industry. Written down in a standards manual. 2 Alphabet of Lines The Alphabet of Lines reveals Shape Size Hidden surfaces Interior detail Alternate positions Etc. of 3 parts, etc. Alphabet of Lines The Alphabet of Lines Look different. Some are Thin width Medium width Thick width The 4 various lines are easily distinguishable. Alphabet of Lines The Alphabet of Lines Object Hidden Center Dimension Extension Phantom Break Datum Construction 5 Alphabet of Lines Refer to Handout The Alphabet of Lines Available on Blackboard 6 7 Line Characteristics All lines should be dense black, Regardless of line type Regardless of width. Thin, dense black Medium weight, dense black Thick weight, dense black Light pencil lines tend to “burn out” during the reproduction process. Make “fuzzy” lines on blueprint/copy. 8 Line Characteristics Lines are uniform within the line. Looks the same width all along the length of the line. Thin – thin all along the length Medium – medium all along the length Thick – thick all along the length 9 Visible Lines EDT 300/306 - Basic Technical Drafting 10 Object/Visible Lines Object/Visible Lines Show the object. Show the outline of the the visible edges or contours of an object that can be seen by an observer. 11 Object/Visible Lines Object/Visible Lines Should stand out sharply when contrasted with other lines on the drawing. Object/Visible Medium Lines - Spacing and Size. width. Continuous line (no dashes) Dense black. 12 Visible Lines 13 Hidden Lines EDT 300/306 - Basic Technical Drafting 14 Hidden Lines Hidden Lines Show Edges Surfaces Corners of an object that are concealed from the view of the observer. 15 Hidden Lines Hidden Lines Spacing and Size Thin lines. Evenly space short dashes Approximately 1/8” long, Spaces 1/32” long. Dense 16 black. Hidden Lines Hidden Line “Rules” 1. Start and end with a dash. 2. If a hidden line is a continuation of a visible line then a gap is shown. 3. A gap is also shown when a hidden line crosses but does not intersect another line. Hidden lines should be omitted when they are not needed for clarity. 17 Hidden Lines 18 Center Lines EDT 300/306 - Basic Technical Drafting 19 Center Lines Center Lines Show 1. Axes of symmetrical parts 2. Centers of circles and 3. Paths of motion. 20 Center Lines Center Lines - Spacing and Size. Thin lines. Alternating long and short dashes. The long dash (3/4” to 1-1/2”) The short dash (1/16” to 1/8”) Dense 21 black. Center Lines Center Lines “Rules” 1. Center lines intersect at the short dashes. 2. Center lines extend only a short distance past the object. 3. Center lines start and end with a long dash. 22 Center Lines 23 Dimension Lines Extension Lines Leaders EDT 300/306 - Basic Technical Drafting 24 Dimension Lines, Extension Lines and Leaders Dimension lines Indicate the size and direction of dimensions. Are terminated by arrowheads. Dimension Thin Lines - Spacing and Size lines. Continuous. Dense black. 25 Dimension Lines, Extension Lines and Leaders 26 Dimension Lines, Extension Lines and Leaders Extension lines Indicate the termination of a dimension. Extend from approximately 1/16 inch from the object to 1/8 inch beyond the last arrowhead. Extension Thin Lines - Spacing and Size lines. Dense black. Continuous lines. 27 Dimension Lines, Extension Lines and Leaders 28 Dimension Lines, Extension Lines and Leaders Leaders Are drawn to notes or identification symbols used on the drawing. Start with 1/8 “shoulder” End with arrowhead. Leaders Thin - Spacing and Size lines. Continuous lines. Dense black. 29 Leader Lines 30 Cutting Plane Lines EDT 300/306 - Basic Technical Drafting 31 Cutting Plane Lines Cutting Plane Lines Indicate the location of the edge view of the cutting plane. Cutting Plane Lines - Spacing and Size Thick line. Dense black. Two 32 forms are approved for general use. Cutting Plane Lines Cutting Plane Lines First Form Alternating long dashes (3/4” to 1 1/2”) and pairs of short dashes (1/8” with 1/16” space). Second Equal Both Form dashes 1/4” in length. forms bent at 90o and Ends are terminated by arrowheads to indicate the direction of viewing of the section. Arrow stems are continuous lines.1 Ends 33 Cutting Plane Lines 34 Section Lines EDT 300/306 - Basic Technical Drafting 35 Section Lines Section Lines Represent surfaces exposed by a cutting plane passing through an object. Sometimes called “cross-hatching”. “hatching” Drawn pencil. 36 at an angle of 45o with a sharp 2H Section Lines Section Lines - Spacing and Size Thin lines Continuous lines. Dense black. Space about 1/8” apart. small Space lines close together large drawings - 3/16” Space lines further apart. Make 37 drawings - 1/32 line spacing uniform. Section Lines 38 Break Lines EDT 300/306 - Basic Technical Drafting 39 Break Lines Break lines Show the limit of a partial view of a broken section. For short breaks, a thick line is drawn freehand. Usually used for mechanical work. For A large breaks long, thin line joined by freehand “zig-zags”. Usually used for architectural work. 40 Break Lines Break Lines - Spacing and Size Thick. Dense black. Freehand. Continuous. Thin Dense black Straight line with freehand “zig” Continous. 41 Break Lines 42 Phantom Lines EDT 300/306 - Basic Technical Drafting 43 Phantom Lines Phantom lines: Show Alternate positions. Repeated details. Paths of motion. Phantom Thin Lines - Spacing and Size lines. Dense black. Long dashes 3/4” to 1-1/2” in length with alternating with pairs of short dashes 1/8” long with 1/16” spacing between the dashes. 44 Phantom Lines 45 Datum Lines EDT 300/306 - Basic Technical Drafting 46 Datum Dimensions Datum Lines Show Lines points surfaces assumed that are to be accurate. Are placed on drawings as datum dimensions since they may be used for exact reference and location purposes. 47 Datum Dimensions Datum Lines - Spacing and Size Thin lines. Dense black. Thin, long dashes - 3/4” to 1-1/2” long alternating with Pairs 48 of short dashes - 1/8” long 1/16” spacing between the dashes. Construction Lines EDT 300/306 - Basic Technical Drafting 49 Construction Lines Construction Lines Used to lay out all work PRIOR to drawing ANY object lines. Drawn very light so they will not reproduce when making a blue print. (They should not be visible when viewing beyond an arm’s length from the drawing.) Construction Thin Lines - Spacing and Size lines. Light gray lines. Draw with very hard pencil 2H, 3H, 4H. 50 Border Lines EDT 300/306 - Basic Technical Drafting 51 Border Lines Border lines Are the “frame” of the drawing. Spacing and Size Thickest lines. Dense black. Continuous. Border 52 lines are the heaviest of all lines.